The detoxification of hazardous waste such as certain organic compounds, chemical and biological warfare weapons, and low and high level radioactive waste, is an ongoing problem. The shipment of such waste to processing or disposal sites creates significant danger of environmental release in the event of an accident. Accordingly, there is a need for methods and systems to efficiently dispose or reduce the volume of such toxic waste at the site where the waste is located.
The use of incinerators for burning hazardous waste is becoming unacceptable. Incinerators that meet current air pollution laws and have efficient operation tend to be relatively large and therefore may not be economically feasible for placement at facilities where toxic waste is generated. Moreover, incinerators are often difficult to control and create strong community and political ill-feeling. Perhaps more importantly, however, the incineration process may produce other toxic products which are themselves undesirable and which are difficult or impossible to eliminate.
In U.S. Pat. No. 4,874,587, issued Oct. 17, 1989 and assigned to the assignee of the present invention, a process and apparatus are described for hazardous waste detoxification which represent a significant improvement over incinerators. In the aforesaid patent, a reactor is described in which toxic destruction levels of 99.99% or more are achieved. The aforesaid process and apparatus are operated without air or free oxygen reaction and produce an effluent gas which is primarily comprised of carbon dioxide, hydrogen, carbon monoxide and water. The process and apparatus described in the aforesaid patent has been classified by the United States Environmental Protection Agency as "infrared heater" as differentiated from "incineration". Federal Register No. 57, Aug. 25, 1992, pp. 8558-38564, EPA memorandum Sep. 30, 1991 from Sylvia Lowrance, Dir., Solid Waste to Allyn M. Davis, Dir., Region 6.
A steam-reforming detoxification reactor operates to react a gaseous stream of toxic material with water in excess of the stoichiometric amount necessary to react with substantially all of the organic compounds in the stream of toxic waste. This reaction is carried out at a temperature in excess of about 1000.degree. C. and results in an effluent gas stream of high temperature comprised primarily of carbon dioxide, water, and hydrogen but also containing low levels of carbon monoxide. The latter can be readily converted later to carbon dioxide by catalytic oxidation.
Since the principal reaction in a steam-reforming detoxification reactor occurs in the gas phase, the processing of waste where the waste material can be relatively easily gasified is fairly straightforward. For example, a system for vaporizing and gasifying toxic waste for feeding to a steam-reforming detoxification reactor wherein the toxic waste is liquid contained in a metal drum is shown and described in U.S. Pat. No. 4,863,702, issued on Sep. 5, 1989 and assigned to the assignee of the present invention. In the case of certain materials, such as viscous liquids and slurries, or more stable organic or inorganic compounds, however, conversion of the waste into a gaseous form for feeding to a steam-reforming detoxification reactor is not easily accomplished by the system described in the aforesaid patent.
Accordingly, it is a general object of this invention to provide an improved method and system for detoxifying toxic waste.
Another object of the invention is to provide an improved method for detoxifying liquid or slurry toxic waste which employs a steam-reforming detoxification reactor and which is adaptable to on-site applications.
Still another object of the invention is to provide an improved method and apparatus for detoxifying liquid or slurry toxic waste which operate efficiently and substantially completely.
A more general object of the invention is to provide an improved method and apparatus for processing liquid or slurry feed material to derive output product of an altered character.
Other objects of the invention will become apparent to those skilled in the art from the following description and accompanying drawings.